<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
    <meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
    <title>图片轮播 js原生(左右切换)</title>
    <style type="text/css">
        body,div,ul,li,a,img{margin: 0;padding: 0;}
        ul,li{list-style: none;}
        a{text-decoration: none;}

        #wrapper{position: relative;margin: 30px auto;width: 400px;height: 200px;}
        #banner{position:relative;width: 400px;height: 200px;overflow: hidden;}
        .imgList{position:relative;width:2000px;height:200px;z-index: 10;overflow: hidden;}
        .imgList li{float:left;display: inline;}
        #prev,
        #next{position: absolute;top:80px;z-index: 20;cursor: pointer;opacity: 0.2;filter:alpha(opacity=20);}
        #prev{left: 10px;}
        #next{right: 10px;}
        #prev:hover,
        #next:hover{opacity: 0.5;filter:alpha(opacity=50);}
        .bg{position: absolute;bottom: 0;width: 400px;height: 40px;z-index:20;opacity: 0.4;filter:alpha(opacity=40);background: black;}
        .infoList{position: absolute;left: 10px;bottom: 10px;z-index: 30;}
        .infoList li{display: none;}
        .infoList .infoOn{display: inline;color: white;}
        .indexList{position: absolute;right: 10px;bottom: 5px;z-index: 30;}
        .indexList li{float: left;margin-right: 5px;padding: 2px 4px;border: 2px solid black;background: grey;cursor: pointer;}
        .indexList .indexOn{background: red;font-weight: bold;color: white;}
    </style>
</head>
<body>
<div id="wrapper"><!-- 最外层部分 -->
    <div id="banner"><!-- 轮播部分 -->
        <ul class="imgList"><!-- 图片部分 -->
            <li><a href="#"><img src="./img/test1.jpg" width="400px" height="200px" alt="puss in boots1"></a></li>
            <li><a href="#"><img src="./img/test2.jpg" width="400px" height="200px" alt="puss in boots2"></a></li>
            <li><a href="#"><img src="./img/test3.jpg" width="400px" height="200px" alt="puss in boots3"></a></li>
            <li><a href="#"><img src="./img/test4.jpg" width="400px" height="200px" alt="puss in boots4"></a></li>
            <li><a href="#"><img src="./img/test5.jpg" width="400px" height="200px" alt="puss in boots5"></a></li>
        </ul>
        <img src="./img/prev.png" width="20px" height="40px" id="prev">
        <img src="./img/next.png" width="20px" height="40px" id="next">
        <div class="bg"></div> <!-- 图片底部背景层部分-->
        <ul class="infoList"><!-- 图片左下角文字信息部分 -->
            <li class="infoOn">puss in boots1</li>
            <li>puss in boots2</li>
            <li>puss in boots3</li>
            <li>puss in boots4</li>
            <li>puss in boots5</li>
        </ul>
        <ul class="indexList"><!-- 图片右下角序号部分 -->
            <li class="indexOn">1</li>
            <li>2</li>
            <li>3</li>
            <li>4</li>
            <li>5</li>
        </ul>
    </div>
</div>
<script type="text/javascript">
    var curIndex = 0, //当前index
            imgArr = getElementsByClassName("imgList")[0].getElementsByTagName("li"), //获取图片组
            imgLen = imgArr.length,
            infoArr = getElementsByClassName("infoList")[0].getElementsByTagName("li"), //获取图片info组
            indexArr = getElementsByClassName("indexList")[0].getElementsByTagName("li"); //获取控制index组
    // 定时器自动变换2.5秒每次
    var autoChange = setInterval(function(){
        if(curIndex < imgLen -1){
            curIndex ++;
        }else{
            curIndex = 0;
        }
        //调用变换处理函数
        changeTo(curIndex);
    },2500);

    //清除定时器时候的重置定时器--封装
    function autoChangeAgain(){
        autoChange = setInterval(function(){
            if(curIndex < imgLen -1){
                curIndex ++;
            }else{
                curIndex = 0;
            }
            //调用变换处理函数
            changeTo(curIndex);
        },2500);
    }

    //调用添加事件处理
    addEvent();

    //给左右箭头和右下角的图片index添加事件处理
    function addEvent(){
        for(var i=0;i<imgLen;i++){
            //闭包防止作用域内活动对象item的影响
            (function(_i){
                //鼠标滑过则清除定时器，并作变换处理
                indexArr[_i].onmouseover = function(){
                    clearTimeout(autoChange);
                    changeTo(_i);
                    curIndex = _i;
                };
                //鼠标滑出则重置定时器处理
                indexArr[_i].onmouseout = function(){
                    autoChangeAgain();
                };
            })(i);
        }

        //给左箭头prev添加上一个事件
        var prev = document.getElementById("prev");
        prev.onmouseover = function(){
            //滑入清除定时器
            clearInterval(autoChange);
        };
        prev.onclick = function(){
            //根据curIndex进行上一个图片处理
            curIndex = (curIndex > 0) ? (--curIndex) : (imgLen - 1);
            changeTo(curIndex);
        };
        prev.onmouseout = function(){
            //滑出则重置定时器
            autoChangeAgain();
        };

        //给右箭头next添加下一个事件
        var next = document.getElementById("next");
        next.onmouseover = function(){
            clearInterval(autoChange);
        };
        next.onclick = function(){
            curIndex = (curIndex < imgLen - 1) ? (++curIndex) : 0;
            changeTo(curIndex);
        };
        next.onmouseout = function(){
            autoChangeAgain();
        };
    }

    //左右切换处理函数
    function changeTo(num){
        //设置image
        var imgList = getElementsByClassName("imgList")[0];
        goLeft(imgList,num*400); //左移一定距离
        //设置image 的 info
        var curInfo = getElementsByClassName("infoOn")[0];
        removeClass(curInfo,"infoOn");
        addClass(infoArr[num],"infoOn");
        //设置image的控制下标 index
        var _curIndex = getElementsByClassName("indexOn")[0];
        removeClass(_curIndex,"indexOn");
        addClass(indexArr[num],"indexOn");
    }


    //图片组相对原始左移dist px距离
    function goLeft(elem,dist){
        if(dist == 400){ //第一次时设置left为0px 或者直接使用内嵌法 style="left:0;"
            elem.style.left = "0px";
        }
        var toLeft; //判断图片移动方向是否为左
        dist = dist + parseInt(elem.style.left); //图片组相对当前移动距离
        if(dist<0){
            toLeft = false;
            dist = Math.abs(dist);
        }else{
            toLeft = true;
        }
        for(var i=0;i<= dist/20;i++){ //这里设定缓慢移动，10阶每阶40px
            (function(_i){
                var pos = parseInt(elem.style.left); //获取当前left
                setTimeout(function(){
                    pos += (toLeft)? -(_i * 20) : (_i * 20); //根据toLeft值指定图片组位置改变
                    //console.log(pos);
                    elem.style.left = pos + "px";
                },_i * 25); //每阶间隔50毫秒
            })(i);
        }
    }

    //通过class获取节点
    function getElementsByClassName(className){
        var classArr = [];
        var tags = document.getElementsByTagName('*');
        for(var item in tags){
            if(tags[item].nodeType == 1){
                if(tags[item].getAttribute('class') == className){
                    classArr.push(tags[item]);
                }
            }
        }
        return classArr; //返回
    }

    // 判断obj是否有此class
    function hasClass(obj,cls){  //class位于单词边界
        return obj.className.match(new RegExp('(\\s|^)' + cls + '(\\s|$)'));
    }
    //给 obj添加class
    function addClass(obj,cls){
        if(!this.hasClass(obj,cls)){
            obj.className += cls;
        }
    }
    //移除obj对应的class
    function removeClass(obj,cls){
        if(hasClass(obj,cls)){
            var reg = new RegExp('(\\s|^)' + cls + '(\\s|$)');
            obj.className = obj.className.replace(reg,'');
        }
    }
</script>
</body>
</html>